Current-Sense Amplifier Offset Reduction by Transistor Selection
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Solution Overview
Problem
Current current-sense amplifiers in memory integrated circuits face issues with large voltage or current offsets due to asymmetrically arranged transistors in differential current mirrors, leading to unstable detection accuracy and reduced data read speed.
Innovation Solution
A low-offset current-sense amplifier design comprising a sense amplifier, first and second current supply units, and a processing unit, where the processing unit controls transistors in these units to on or off based on electric currents, allowing for the selection of transistors with smaller current offsets, thereby reducing the current offset of the differential current mirror.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If transistors are arranged asymmetrically in a differential current mirror, then device complexity is reduced, but current offset increases leading to unstable detection accuracy
Solution Approach 1:
The patent applies preliminary action by measuring and evaluating transistor current offsets before the sense amplifier operation. The processing unit measures currents from multiple transistor groups and identifies transistors with smaller offsets in advance, selecting them for use in the differential current mirror. This pre-selection ensures low offset performance without requiring complex asymmetric arrangements during operation.
Solution Approach 2:
The patent changes the selection criterion for transistors based on their current offset parameters. Instead of using fixed asymmetric arrangements, the system dynamically selects transistors whose current offset parameters fall within a predetermined acceptable range. The processing unit adjusts which transistors are activated based on their measured performance parameters, ensuring optimal detection accuracy.
2Measurement precision
If transistors with smaller current offsets are selected, then detection accuracy improves, but device complexity increases due to multiple transistor groups and control logic
Solution Approach 1:
The patent segments the transistor population into multiple groups (first, second, third, and fourth transistor groups) with different current supply configurations. Each group can be independently controlled and measured. This segmentation allows the system to evaluate and select from diverse transistor characteristics without requiring a completely complex unified structure, as each segment can be optimized independently.
Solution Approach 2:
The system implements self-service by having the processing unit automatically measure, evaluate, and select transistors with appropriate current offset characteristics. The first and second current supply units provide currents to multiple transistor groups, and the processing unit autonomously determines which transistors meet the predetermined offset criteria. This automated selection process reduces the need for external calibration and manual adjustment.
3Adaptability or versatility
If multiple current supply units with multiple transistor groups are used, then transistor selection flexibility increases, but use of energy increases
Solution Approach 1:
The patent implements periodic action by sequentially activating different transistor groups for measurement and evaluation rather than continuously powering all groups. The processing unit measures currents from the first and second transistor groups, evaluates their offsets, and then selects appropriate transistors for operation. This periodic measurement and selection approach reduces continuous power consumption compared to keeping all transistor groups actively powered.
Data Source
AI summary
A low-offset current-sense amplifier and an operating method thereof are disclosed. The low-offset current-sense amplifier includes a sense amplifier, a first current supply unit, a second current supply unit, and a processing unit. The first current supply unit is coupled to the sense amplifier, and includes a first transistor group and a first current output terminal. The second current supply unit is coupled to the sense amplifier, and includes a second transistor group and a second current output terminal. The processing unit controls the on/off of some transistors of the first transistor group and the second transistor group according to electric currents output from the first current output terminal and the second current output terminal, respectively.